title: Do bone loss and reconstruction procedures differ at revision of cemented unicompartmental knee prostheses according to the use of metal-back or all-polyethylene tibial component?
abstract: BACKGROUND
  Results of unicompartmental knee arthroplasty (UKA) revision are known but the severity of bone loss and the need for reconstruction are not detailed for different tibial implants.
  
  
  OBJECTIVE
  Metal-backing UKA revision exposes the patient to more severe tibial bone loss and requires more substantial reconstruction procedures than cemented polyethylene UKA revision.
  
  
  METHODS
  This retrospective series of 23 revisions of UKA to total knee arthroplasty (TKA) compared 11 all-polyethylene UKAs with 12 metal-backing UKAs. Factors that contributed to failure were aseptic loosening (n=12) and osteoarthritis evolution (n=11). Both groups were similar regarding the demographic and clinical features. We reported bone loss and the reconstruction procedure to fill it according to the initially used tibial implant. The results were evaluated with the IKS score to a follow-up of 37 months (range, 24-67 months).
  
  
  RESULTS
  There were more tibial segmental bone loss (10 versus 3) and more metal wedges (8/12 versus 2/11) in metal-backing UKA revision (P<0.05). Tibial stems were more often used in metal-backing UKA revision (12/12 versus 7/11) (P=0.04). The results of TKA at follow-up did not differ according to whether the revised tibial implant was all polyethylene (IKS=155 [range, 107-195]) or metal-back (IKS=155 [range, 127-172]).
  
  
  CONCLUSIONS
  This study suggests that metal-backing UKA revision exposes the patient to more severe tibial bone loss requiring more substantial reconstruction. These results must be confirmed on a larger population, but surgeons should be alerted to this kind of revision surgery, which warrants having available a revision knee prothesis.
  
  
  METHODS
  Level III, case-control study.
authors.affiliation: Université Lille Nord de France, 59000 Lille, France; Services d'orthopédie, département universitaire de chirurgie orthopédique, université Lille 2, hôpital Salengro, CHRU de Lille, place de Verdun, 59037 Lille cedex, France. Electronic address: thomas.rouanet@gmail.com.
authors.forename: T
authors.initials: T
authors.lastname: Rouanet
authors.forename: A
authors.initials: A
authors.lastname: Combes
authors.forename: H
authors.initials: H
authors.lastname: Migaud
authors.forename: G
authors.initials: G
authors.lastname: Pasquier
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects* / Q000379:methods; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007720:Knee Prosthesis; D008297:Male; D008670:Metals; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000601:surgery*; D010024:Osteoporosis / Q000150:complications* / Q000175:diagnosis; D010147:Pain Measurement; D020959:Polyethylene; D011474:Prosthesis Design; D011475:Prosthesis Failure / Q000209:etiology*; D011859:Radiography; D020127:Recovery of Function; D012086:Reoperation / Q000379:methods; D012189:Retrospective Studies; D018570:Risk Assessment; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D008670:Metals; D020959:Polyethylene
keywords: Bone loss; Reconstruction; Revision; Unicompartmental knee prosthesis